early 15c., "action of gathering together," from Middle French congestion (14c.), from Latin congestionem (nominative congestio), noun of action from past participle stem of congerere (see congest). Medical sense is from 1630s; meaning "a crowding together of people, traffic, etc." is from 1883.

African nation, named for the river that runs through it, which is from a Bantu word meaning "mountains" (i.e., the river that flows from the mountains). As an adjective, Congoese is native English (1797) but has been supplanted by Congolese (1900), from French Congolais.

mid-14c., "a gathering, assembly," from Old French congregacion (12c., Modern French congrégation), from Latin congregationem (nominative congregatio), noun of action from congregare (see congregate).

Used by Tyndale to translate Greek ekklesia in New Testament and by some Old Testament translators in place of synagoge. (Vulgate uses a variety of words in these cases, including congregatio but also ecclesia, vulgus, synagoga, populus.) Protestant reformers in 16c. used it in place of church; hence the word's main modern sense of "local society of believers" (1520s).

1630s, in reference to Congregationalism, a Protestant movement in which church congregations were to be self-governing (the term most used in New England, in Britain they were called Independent); from congregation + -al (1). Related: Congregationalist.

Sense of "meeting of delegates" is first recorded 1670s. Meaning "sexual union" is from 1580s. Used in reference to the national legislative body of the American states since 1775 (though since 1765 in America as a name for proposed bodies). Congress of Vienna met Nov. 1, 1814, to June 8, 1815, and redrew the map of Europe with an eye to creating a balance of powers after the disruptions of Napoleon.

1690s, from Latin congressionem (from congressus, see congress) + -al (1). Originally sometimes reviled as barbarous, Pickering (1816) quotes an unnamed English correspondent: "The term Congress belonging to America, the Americans may employ its derivatives, without waiting for the assent of the English."

as in conk out, 1918, coined by World War I airmen, perhaps in imitation of the sound of a stalling motor, reinforced by conk (v.) "hit on the head," originally "punch in the nose" (1821), from conk (n.), slang for "nose" (1812), perhaps from fancied resemblance to a conch (pronounced "conk") shell.